Electrical Test Questions and Answers

1. The diameter of an atom is about

(i) 10-10 m
(ii) 10-8m
(iii) 10-2 m
(iv) 10-15 m

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2. The number of compounds available in nature is

(i) 105
(ii) 300
(iii) 1000
(iv) unlimited

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3. The mass of a proton is …….. the mass of electron.

(i) equal to
(ii) less than
(iii) about 1837 times
(iv) 200 times

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4. The electrons in the last orbit of an atom arc called

(i) free electrons
(ii) bound electrons
(iii) valence electrons
(iv) thermionic electrons

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5. If the number of valence electrons of an atom is less than 4, the substance is usually

(i) a conductor
(ii) an insulator
(iii) a semiconductor
(iv) none of the above

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6. If the number of valence electrons of an atom is more than 4, the substance is usually

(i) a semiconductor
(ii) a conductor
(iii) an insulator
(iv) none of the above.

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7. If the number of valence electrons of an atom is 4, then the substance is usually

(i) a semiconductor
(ii) an insulator
(iii) a conductor
(iv) none of the above

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8. One coulomb of charge is equal to the charge on

(i) 625 x 1016electrons
(ii) 6.25 x 1016electrons
(iii) 62.5 x 1016electrons
(iv) 0.625 x 1016 electrons

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9. 1 cm3 of copper at room temperature has about

(i) 200 free electrons
(ii) 20 x 1010efree electrons
(iii) 8.5 x 1022 free electrons
(iv) 3 x 105free electrons

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10. The electric current is due to the flow of

(i) positive charges only
(ii) negative charges only
(iii) both positive and negative charges
(iv) neutral particles only

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11. E.M.F. in a circuit

(i) increases circuit resistance
(ii) decreases circuit resistance
(iii) maintains potential difference
(iv) none of the above

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12. The electric current in a metallic conductor is due to the flow of

(i) electrons only
(ii) positive ions only
(iii) electrons and positive ions only
(iv) neutral atoms only

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13. Potential difference has the unit of

(i) charge
(ii) power
(iii) energy
(iv) none of the above

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14. The electric current in a liquid is due to the flow of

(i) electrons only
(ii) positive ions only
(iii) negative and positive ions both
(iv) electrons and positive ions both

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15. Electric current is a

(i) scalar quantity
(ii) vector quantity
(iii) sometimes scalar and sometimes vector
(iv) number only

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16. A billion electrons pass through a cross-section of a conductor in 10-3s. The current is

(1) 10-7A
(ii) 1.6×10-7A
(iii) 2 x 10-4A
(iv) 2.6 x 10-3A

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17. The electric current in a discharge tube containing a gas is due to

(i) electrons only
(ii) positive ions only negative and positivc ions both
(iv) electrons and positive ions both

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18. How long does it take 50 µC of charge to pass a point in a circuit if the current flow is 15mA?

(i) 3.33 x 10-31
(ii) 6 x 102s
(iii) 2 s
(iv) none of the above

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19. The specific resistance of a wire depends upon

(i) its length
(ii) its cross-sectional area
(iii) its dimensions
(iv) its material

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20. The quantity of charge that will be transferred by a current flow of 10 A over 1 hour period is

(i) 10 C
(ii) 3.6 x 104 C
(iii) 2.4 x 102 C
(iv) 1.6 x 102 C

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